Page 21 - Moving the Earth_ The Workbook of Excavation

LAND CLEARING AND CONTROLS

LAND CLEARING AND CONTROLS 1.21

Stumps are a major problem in most clearing that involves trees. They can sometimes be cut
low and left under deep fills, but usually must be removed.
Stumps may be broken out by uprooting the whole tree, then disposed of as part of the tree or
separately. But it is more usual to cut and remove the tree and then take out the stump.
Stumps may be pushed out by powerful dozers; dug out by somewhat less powerful dozers,
rippers, or hoes; pulled out with cables or chains; or blasted. Blasting may be combined with other
methods. It is occasionally practical to burn stumps in the ground.
Once out of the ground, stumps present a problem of disposal. As massive pieces of green
wood caked with dirt, they are difficult to burn. Nevertheless, this is usually the best way to get
rid of them. They are so bulky and irregular in shape that they are hard to bury, and they are an
eyesore in piles. Since they rot, they cannot be used in fills under structures.

PUSHING AND DIGGING OUT

Pushing. Crawler tractors, with dozer blade or loader bucket, or a special narrow stumping
blade, are standard for uprooting by pushing. Stumps should be cut high—at least 36 inches—for
good leverage.
The blade or bucket is lowered to contact the stump a few inches below the top, and the
machine is moved forward in low gear. If the stump yields, forward push is continued until the
trunk leans so far that effective contact is lost, or until the roots bulge in front of the tracks.
The tractor is then backed, and the edge forced under the upturned roots. Lifting while moving
forward slowly should roll the stump out of the ground, breaking all roots except those on the far
side. See Fig. 1.15.
Further pushing to get out the far roots may drop or mire the tractor in the stump hole, or may roll
up a too-big ball of roots and soil. It may be better to finish freeing the stump by going to its other side.
A number of stumps may be overturned in one direction, then the tractor turned to finish them
up from the other.
The same method is followed to uproot a standing tree, except that a high push point is used
for greater leverage, and the capacity of the machine relative to trunk diameter is improved.
Before pushing a tree with any type of machine, the operator should look to make sure that it is
alive or at least sound. If a rotten tree is pushed near the base, it may break high up and a top section
fall on the dozer. Large dead branches are sometimes dropped with equally disastrous consequences.
A dozer to be used extensively for tree pushing should carry overhead guards for the operator.
A tree may bend or split without affecting the roots, in which case the push should be applied
lower on the trunk, or from a different direction.

Digging Out. If it does not yield at all to pushing, it must be dug out. This is done by trenching
around it with the dozer to cut the roots. If done systematically, this may follow the pattern in
Figure 1.16, but frequently it is unnecessary to go through the whole procedure. Each time the

FIGURE 1.15 Two passes to push out a stump.